I am trying to make it so that when you click it will show a different cursor_sprite for 0.25 seconds. I currently need some way to add a delay to this. Here is my code so far:
In create event:
/// #description Set cursor
cursor_sprite = spr_cursor;
In step event:
/// #description If click change cursor
if mouse_check_button_pressed(mb_left)
{
cursor_sprite = spr_cursor2;
// I want to add the delay here.
}
You could use the build-in Alarms for this, but I don't like these much when it becomes nested with parent objects.
So instead of Alarms, this is the way I would do it:
Create Event:
cursor_sprite = spr_cursor;
timer = 0;
timermax = 0.25;
I create 2 variables: the timer will be used to count down, and the timermax to reset it's time.
Step Event:
if (timer > 0)
{
timer -= 1/room_speed //decrease in seconds
}
else
{
cursor_sprite = spr_cursor;
}
if mouse_check_button_pressed(mb_left)
{
cursor_sprite = spr_cursor2;
timer = timermax;
}
For each timer, I let it count down in the Step Event through 1/room_speed, that way, it will decrease the value in real-time seconds.
Then you can set the timer through timer = timermax
Then if the timer reaches zero, it'll do the given action afterwards.
Though a reminder that it's in the Step Event, so once the timer reaches zero, it'll always reach the else statement if there are no other conditions before. Usually I use the else-statement to change conditions so it doesn't reach the timer code multiple times.
#Steven:
This is useful as far as it goes, but I think you mixed up the starting values for timer and timermax. If timer is counting down, then it obviously can't start at 0.
Also, starting timer at your intended duration completely obviates the need for even having a second variable (timermax).
So it could go:
Create Event:
cursor_sprite = spr_cursor;
timer = 0.25;
Step Event:
if mouse_check_button_pressed(mb_left)
{
cursor_sprite = spr_cursor2;
timer = 0.25;
}
if (timer > 0)
{
timer -= 1/room_speed //decrease in seconds
}
else
{
cursor_sprite = spr_cursor;
}
I'm facing a troublesome problem while trying to create a game engine in threeJS.
It is a math problem, but also a programming problem.
I've implemented a velocity based movement system for the player's avatar - I've used a tank in this example.
Currently, when the player hits a wall, regardless of the angle, the tank invariably stops dead.
However, I want it to be the case that the tank's velocity changes, having been coerced to follow the angle of the wall, and also reduced by a magnitude that is related to that angle.
For example, in FIG A, upon hitting the wall, the Tank continues to try and move forwards, but it's velocity is altered so that it now moves forwards, and sideways, at a reduced rate.
In FIG B, the tank hits the wall dead-on, and its overall velocity reaches 0.
In FIG C, the tank glances off the wall, and its overall velocity is only reduced by a small amount.
I've realised that I need to somehow combine the Tank's velocity vector with the wall's normal vector, to produce the adjusted vector, but I am struggling with how to represent this mathematically / programmatically.
I've tried using: tank.velocity.multiply(wallFaceNormal); (both tank.velocity and wallFaceNormal are Vector3 objects.) but this only seems to work as intended when the wall is either at angles of 0, 90, 180 or 270.
since a tank will not jump or fly, you should be fine with just a 2D-System for your calculation?
i found a link describing the physics of car hitting a solid brick wall.
http://colgatephys111.blogspot.com/2017/12/guardrail-lessens-force-of-impact.html
hope thats gonna help you a bit!
edit:
so, out of curiosity, i asked an theoretical physicist over the phone about your issue.
you got 2 seperate problems to solve:
1. P1 what is the velocity v' while hitting the wall?
2. P2 what is the new angle of the vehicel?
P2 should be fairly easy, considering your tank is adapting the angle of the wall you only need to calculate in which direction the wall is "pointing".
P1 in physics, we would talk about the reduced force and not the velocity, but given a constant limit to the force F1 (eg. your engine) resulting in a constant maxspeed,
and with a given force the wall has on the vehicel F2
v = F1
v' = F1'
F1' = F1 - F2
i think
https://www.thoughtco.com/what-is-the-physics-of-a-car-collision-2698920
explains what to do
Some code provided by a Physicist, which partly worked when I converted it to Javascript and applied it to the program:
Vector3 wallNormal = new Vector3(-0.5, 0.0, 0.5);
Vector3 incomingVelocity = new Vector3(0.0, 0.0, -1.0);
double magnitudeProduct = wallNormal.Length() * incomingVelocity.Length();
double angleBetweenVelocityAndWall = ((-incomingVelocity).Dot(wallNormal)) / (magnitudeProduct);
double newVelocityMagnitude = incomingVelocity.Length() * Math.Sin(angleBetweenVelocityAndWall);
Vector3 upVector =incomingVelocity.Cross(wallNormal);
Vector3 newDirection = wallNormal.Cross(upVector);
Vector3 newVelocity = newDirection.Normalise() * newVelocityMagnitude;
I've done some work on this problem and produced a mini game "framework" that includes an environment collision and movement attenuation utility.
I've written an article that explains how it works, which can be found here. http://www.socket-two.com/main/resource/hdoc-tutorial
But for the sake of the integrity of the thread, here's an adaptation of the portion that describes one of the approaches that can be used to attenuate motion in a ThreeJS simulation:
...
Crucially, my interest has not been to create games that involve large amount of physics, but just to create games where:
A player cannot walk through walls
A player cannot fall through floors
I've made a handful of attempts at implementing a system that would achieve this behaviour, but none of them have really worked satisfactorily. Until now.
In terms of how the ECS fits into the app architecture, it is a utility class. This is its API shape:
class Planeclamp {
constructor({ floors /*Mesh[]*/, walls /*Mesh[]*/ })
getSafePosition(startingPositionIn /*Vector3*/, intendedPositionIn /*Vector3*/) // Returns safePosition, which is a Vector3
}
As you can see, its a class that accepts two arrays of meshes in its constructor: Meshes that should be treated as floors, and meshes that should be treated as walls. Now of course in reality, there is no clear distinction between a steep floor and a shallow-angled wall, but for the purposes of the simulation, the distinction has a very reasonable integrity, and will simplify the environment collision system logic greatly.
Once you've constructed an instance of the Planeclamp class, you can then invoke it's getSafePosition method, to transform a starting position and an intended position into an attenuated position. Being the discerning reader that you are, you will have deduced that the attenuated position is the intended position, having been changed a bit if any collisions have been detected by the utility.
This is how it can be used in the game loop, to ensure a player does not pass through walls or floors:
const planeclamp = new Planeclamp({
floors: [someFloorMesh, someOtherMesh],
walls: [houseMesh, perimeterMesh, truckMesh],
});
const player = new Player();
console.log(player.cage); // Object3D
let playerPreviousPosition = player.cage.position; // Vector3
function gameLoop(delta) {
const playerIntendedPosition = new Three.Vector3(
playerPreviousPosition.x,
playerPreviousPosition.y + (10 * delta), // i.e. Gravity
playerPreviousPosition.z + (1 * delta), // i.e. Walking forwards
);
let {
safePosition, // Vector3
grounded, // Boolean
groundMaterial, // String
} = planeclamp.getSafePosition(playerPreviousPosition, playerIntendedPosition);
player.cage.position.copy(safePosition);
playerPreviousPosition = player.cage.position; // Vector3
}
And thats about it! If you would like to use this utility, you can find it in the repository. But if you would like to know more about the logic behind its workings, read on.
The Planeclamp.getSafePosition method works out a safe position in two stages. Firstly, it uses a vertical raycaster to take a look at what is underneath the player, to then see if it should stop the player from moving downwards any further. Secondly, it uses horizontal raycasters to see if it should stop the player from moving horizontally. Lets look at the vertical constraint procedure first - this is the more simple of the two steps.
// Before we do anything, create a variable called "gated".
// This will contain the safe new position that we will return at the end of
// the function. When creating it, we let it default to the
// intended position. If collisions are detected throughout the lifecycle
// of this function, these values will be overwritten.
let gated = {
x: intendedPosition.x,
y: intendedPosition.y,
z: intendedPosition.z,
};
// Define the point in 3D space where we will shoot a ray from.
// For those who haven't used raycasters before, a ray is just a line with a direction.
// We use the player's intended position as the origin of the ray, but we
// augment this by moving the origin up a little bit (backStepVert) to prevent tunneling.
const start = intendedPosition.clone().sub(new Three.Vector3(
0,
(backStepVert * -1) - (heightOffset / 2),
0)
);
// Now, define the direction of the ray, in the form of a vector.
// By giving the vector X and Z values of 0, and a Y value of -1,
// the ray shoots directly downwards.
const direction = new Three.Vector3(0, -1, 0).normalize();
// We now set the origin and direction of a raycaster that we instantiated
// in the class constructor method.
this.raycasters.vert.set(start, direction);
// Now, we use the `intersectObjects` method of the ray.
// This will return to us an array, filled with information about each
// thing that the ray collided with.
const dirCollisions = this.raycasters.vert.intersectObjects(this.floors, false);
// Initialise a distanceToGround, a grounded variable, and a groundMaterial variable.
let distanceToGround = null;
let grounded = false;
let groundMaterial = null;
// If the dirCollisions array has at least one item in it, the
// ray passed through one of our floor meshes.
if (dirCollisions.length) {
// ThreeJS returns the nearest intersection first in the collision
// results array. As we are only interested in the nearest collision,
// we pluck it out, and ignore the rest.
const collision = dirCollisions[0];
// Now, we work out the distance between where the players feet
// would be if the players intended position became the players
// actual position, and the collided object.
distanceToGround = collision.distance - backStepVert - heightOffset;
// If the distance is less than 0, then the player will pass through
// the groud if their intended position is allowed to become
// their actual position.
if (distanceToGround < 0) {
// We dont want that to hapen, so lets set the safe gated.y coordinate
// to the y coordinate of the point in space at which the collision
// happened. In other words, exactly where the ground is.
gated.y = intendedPosition.y - distanceToGround;
// Make a note that the player is now grounded.
// We return this at the end of the function, along with
// the safe position.
grounded = true;
// If the collided object also has a groundMaterial set inside
// its userData (the place that threeJS lets us attach arbitrary
// info to our objects), also set the groundMaterial. This is
// also returned at the end of the function alongside the grounded
// variable.
if (collision.object.userData.groundMaterial) {
groundMaterial = collision.object.userData.groundMaterial;
}
}
}
And thats it for vertical environment constraints. Simples!
The horizontal environment constraint system is a bit more complex. But in its essence, what it does is:
Work out the horizontal direction the player is travelling in. In olde worlde terms, this can be thought of as North, South, SouthEast, SouthSouthWest etc, but in ThreeJS it is represented by a Vector.
Cast a ray in the direction that the player is travelling in.
Use the ray to find out if allowing the players intended position would cause the player to pass through any of the wall meshes.
And it is at this point that the horizontal ECS becomes more complex than the vertical ECS. With the vertical ECS, if a collision happens, we can just set the players Y position to the Y position of the point at which the collision happened - effectively halting the players Y movement. However, it we did this for horizontal movement, it would make for a very frustrating game experience.
If the player was running head on into a wall, and was stopped dead in their tracks, this would be fine. But if the player moved into the wall at a very shallow angle, and merely grazed it, it would appear that they had "gotten stuck" on the wall, and would find themselves having to reverse away from it, and take care not to touch it again.
What we actually want to happen, is have the player's horizontal velocity attenuated, so that they move along the wall. Therefore, the horizontal ECS proceeds as follows:
Obtain the normal of the surface that was collided with. (For our purposes, a normal can be described as the direction that the wall is facing)
Inspect the difference between the wall normal direction, and the player's movement direction.
Use the difference to work out a safe position, which is the point in space that the collision happened, incremented by a vector that is horizontally perpendicular to the wall normal, multiplied by the cross product of the players input direction and the wall normal.
...
Here is the final utility class, in full:
import * as Three from '../../../vendor/three/three.module.js';
class Planeclamp {
constructor({
scene,
floors = [],
walls = [],
drawRays = true,
} = {}) {
this.drawRays = drawRays;
this.floors = [];
this.walls = [];
this.scene = scene;
this.objects = [];
// Init collidable mesh lists
this.addFloors(floors);
this.addWalls(walls);
// Create rays
this.raycasters = {
vert: new Three.Raycaster(),
horzLeft: new Three.Raycaster(),
horzRight: new Three.Raycaster(),
correction: new Three.Raycaster(),
};
}
setDrawRays(draw) {
this.drawRays = draw;
}
addFloor(floor) {
this.floors.push(floor);
}
removeFloor(floor) {
this.floors = this.floors.filter(thisFloor => thisFloor !== floor);
}
addFloors(floors) {
floors.forEach(floor => this.addFloor(floor));
}
resetFloors() {
this.floors = [];
}
addWall(wall) {
this.walls.push(wall);
}
removeWall(wall) {
this.walls = this.walls.filter(thisWall => thisWall !== wall);
}
addWalls(walls) {
walls.forEach(wall => this.addWall(wall));
}
resetWalls() {
this.walls = [];
}
getSafePosition(startingPositionIn, intendedPositionIn, {
collisionPadding = .5,
heightOffset = 0,
} = {}) {
// ------------------ Setup -------------------
// Parse args
const startingPosition = startingPositionIn.clone();
const intendedPosition = intendedPositionIn.clone();
let grounded = false;
let groundMaterial = null;
// Augmenters
const backStepVert = 50;
const backStepHorz = 5;
const backStepCorrection = 5;
// Prepare output
let gated = {
x: intendedPosition.x,
y: intendedPosition.y,
z: intendedPosition.z,
};
// Clean up previous debug visuals
this.objects.map(object => this.scene.remove(object));
this.objects = [];
// ------------------ Vertical position gating -------------------
// Adjust vertical position in gated.y.
// Store grounded status in grounded.
const start = intendedPosition.clone().sub(new Three.Vector3(
0,
(backStepVert * -1) - (heightOffset / 2),
0)
);
const direction = new Three.Vector3(0, -1, 0).normalize();
this.raycasters.vert.set(start, direction);
const dirCollisions = this.raycasters.vert.intersectObjects(this.floors, false);
if (this.drawRays) {
const arrowColour = dirCollisions.length ? 0xff0000 : 0x0000ff;
const arrow = new Three.ArrowHelper(this.raycasters.vert.ray.direction, this.raycasters.vert.ray.origin, 300, arrowColour);
this.objects.push(arrow);
}
let distanceToGround = null;
if (dirCollisions.length) {
const collision = dirCollisions[0];
distanceToGround = collision.distance - backStepVert - heightOffset;
if (distanceToGround < 0) {
gated.y = intendedPosition.y - distanceToGround;
grounded = true;
if (collision.object.userData.groundMaterial) {
groundMaterial = collision.object.userData.groundMaterial;
}
}
}
// ------------------ Horizontal position gating -------------------
const horizontalOutputPosition = (() => {
// Init output position
const outputPosition = new Three.Vector3(intendedPosition.x, 0, intendedPosition.z);
// Store normalised input vector
const startingPos = startingPosition.clone();
const intendedPos = intendedPosition.clone();
startingPos.y = startingPositionIn.y + .5;
intendedPos.y = startingPositionIn.y + .5;
let inputVector = intendedPos.clone().sub(startingPos).normalize();
// Work out distances
const startingIntendedDist = startingPos.distanceTo(intendedPos);
const inputSpeed = startingIntendedDist;
// Define function for moving ray left and right
function adj(position, offset) {
const rayAdjuster = inputVector
.clone()
.applyAxisAngle(new Three.Vector3(0, 1, 0), Math.PI / 2)
.multiplyScalar(.5)
.multiplyScalar(offset);
return position.clone().add(rayAdjuster);
}
// Work out intersections and collision
let collisions = {
left: {
collision: null
},
right: {
collision: null
}
};
Object.keys(collisions).forEach(side => {
const rayOffset = side === 'left' ? -1 : 1;
const rayStart = adj(startingPos.clone().sub(inputVector.clone().multiplyScalar(2)), rayOffset);
const startingPosSide = adj(startingPos, rayOffset);
const intendedPosSide = adj(intendedPos, rayOffset);
const startingIntendedDistSide = startingPosSide.distanceTo(intendedPosSide);
const rayKey = 'horz' + _.startCase(side);
this.raycasters[rayKey].set(rayStart, inputVector);
const intersections = this.raycasters[rayKey].intersectObjects(this.walls, true);
for (let i = 0; i < intersections.length; i++) {
if (collisions[side].collision) break;
const thisIntersection = intersections[i];
const startingCollisionDist = startingPosSide.distanceTo(thisIntersection.point);
if (startingCollisionDist - collisionPadding <= startingIntendedDistSide) {
collisions[side].collision = thisIntersection;
collisions[side].offset = rayOffset;
}
}
if (inputSpeed && this.drawRays) {
this.objects.push(new Three.ArrowHelper(this.raycasters[rayKey].ray.direction, this.raycasters[rayKey].ray.origin, 300, 0x0000ff));
}
});
const [ leftCollision, rightCollision ] = [ collisions.left.collision, collisions.right.collision ];
const collisionData = (leftCollision?.distance || Infinity) < (rightCollision?.distance || Infinity) ? collisions.left : collisions.right;
if (collisionData.collision) {
// Var shorthands
const collision = collisionData.collision;
const normalVector = collision.face.normal.clone();
normalVector.transformDirection(collision.object.matrixWorld);
normalVector.normalize();
// Give output a baseline position that is the same as the collision position
let paddedCollision = collision.point.clone().sub(inputVector.clone().multiplyScalar(collisionPadding));
paddedCollision = adj(paddedCollision, collisionData.offset * -1);
outputPosition.x = paddedCollision.x;
outputPosition.z = paddedCollision.z;
if (leftCollision && rightCollision && leftCollision.face !== rightCollision.face) {
return startingPos;
}
// Work out difference between input vector and output / normal vector
const iCAngleCross = inputVector.clone().cross(normalVector).y; // -1 to 1
// Work out output vector
const outputVector = (() => {
const ivn = inputVector.clone().add(normalVector);
const xMultiplier = ivn.x > 0 ? 1 : -1;
const zMultiplier = ivn.z > 0 ? 1 : -1;
return new Three.Vector3(
Math.abs(normalVector.z) * xMultiplier,
0,
Math.abs(normalVector.x) * zMultiplier,
).normalize();
})();
if (inputSpeed && this.drawRays) {
this.objects.push(new Three.ArrowHelper(normalVector, startingPos, 300, 0xff0000));
}
// Work out output speed
const outputSpeed = inputSpeed * Math.abs(iCAngleCross) * 0.8;
// Increment output position with output vector X output speed
outputPosition.add(outputVector.clone().multiplyScalar(outputSpeed));
}
// ------------------ Done -------------------
return outputPosition;
})();
gated.x = horizontalOutputPosition.x;
gated.z = horizontalOutputPosition.z;
// ------------------ Culmination -------------------
// Add debug visuals
this.objects.map(object => this.scene.add(object));
// Return gated position
const safePosition = new Three.Vector3(gated.x, gated.y, gated.z);
return { safePosition, grounded, groundMaterial };
}
}
export default Planeclamp;
I'm facing a programming question in which I want to trigger some code whenever a capacitive touch sensor has been touched for 100 ms (to distinguish false positives in my prototype). My sensor is touched by this code
if (digitalRead(touchPin))
Now whenever it has been touched for 100ms I want some other code (for instance, activating a LED) to run. I can't really seem to find a solution because my startTime = millis() variable keeps resetting.
Does anyone know how to tackle this problem?
You need a bool variable, to store last state (TRUE if touched and FALSE if not)
Also, you need to store time when it has been changed to TRUE. Time could be taken by millis() function
If your bool variable is true, check, if time passed is more than your 100 ms.
So:
// In your global scope:
...
// Last touch state
bool isTouched = FALSE;
// time, when last touch happened
int touched_t = 0;
// In your loop:
...
bool isTouchedNow = (digitalRead(touchPin) == HIGH);
// Touch state is changed till last measure:
if (isTouchedNow != isTouched)
{
// Set "last isTouched state" to new one
isTouched = isTouchedNow;
// If it wasn't touched before, store current time (else zero):
touched_t = isTouched ? millis() : 0;
}
else //If touch state isn't changed till last time:
{
//If state was "touched" and now it "touched", and 100ms has passed:
if (isTouched && touched_t > 0 && millis() - touched_t > 100)
{
// Call your function, that should be called,
// whan sensor is touched for 100 ms (activate a LED of something)
DOTHESTUFF();
}
}
...
I am having problem with RTC alarm interrupt of STM32L151. I want my program to go to RTC alarm interrupt every second but it does not work.
My main funtion:
int main(void)
{
HAL_Init();
SystemClock_Config();
MX_GPIO_Init();
MX_IWDG_Init();
MX_RTC_Init();
MX_SPI1_Init();
MX_USART1_UART_Init();
__HAL_RTC_ALARM_ENABLE_IT(&hrtc, RTC_IT_ALRA);
while (1)
{
}
}
Function configures RTC: MX_RTC_Init():
void MX_RTC_Init(void)
{
RTC_TimeTypeDef sTime;
RTC_DateTypeDef sDate;
RTC_AlarmTypeDef sAlarm;
hrtc.Instance = RTC;
hrtc.Init.HourFormat = RTC_HOURFORMAT_24;
hrtc.Init.AsynchPrediv = 127;
hrtc.Init.SynchPrediv = 255;
hrtc.Init.OutPut = RTC_OUTPUT_DISABLE;
hrtc.Init.OutPutPolarity = RTC_OUTPUT_POLARITY_HIGH;
hrtc.Init.OutPutType = RTC_OUTPUT_TYPE_OPENDRAIN;
HAL_RTC_Init(&hrtc);
sTime.Hours = 0x14;
sTime.Minutes = 0;
sTime.Seconds = 0;
sTime.TimeFormat = RTC_HOURFORMAT12_AM;
sTime.DayLightSaving = RTC_DAYLIGHTSAVING_NONE;
sTime.StoreOperation = RTC_STOREOPERATION_RESET;
HAL_RTC_SetTime(&hrtc, &sTime, FORMAT_BCD);
sDate.WeekDay = RTC_WEEKDAY_WEDNESDAY;
sDate.Month = RTC_MONTH_AUGUST;
sDate.Date = 0x24;
sDate.Year = 0x16;
HAL_RTC_SetDate(&hrtc, &sDate, FORMAT_BCD);
/**Enable the Alarm A
*/
sAlarm.AlarmTime.Hours = 0;
sAlarm.AlarmTime.Minutes = 0;
sAlarm.AlarmTime.Seconds = 0;
sAlarm.AlarmTime.TimeFormat = RTC_HOURFORMAT12_AM;
sAlarm.AlarmTime.DayLightSaving = RTC_DAYLIGHTSAVING_NONE;
sAlarm.AlarmTime.StoreOperation = RTC_STOREOPERATION_RESET;
sAlarm.AlarmMask = RTC_ALARMMASK_SECONDS;
sAlarm.AlarmDateWeekDaySel = RTC_ALARMDATEWEEKDAYSEL_DATE;
sAlarm.AlarmDateWeekDay = 1;
sAlarm.Alarm = RTC_ALARM_A;
HAL_RTC_SetAlarm_IT(&hrtc, &sAlarm, FORMAT_BCD);
}
I created project using CubeMX. Do you have any idea or advice for me? Thank you
If a field is masked, then that won't be compared when checking alarm date. So when you mask SECONDS, then only the DAY, HOUR and MINUTE fields will be compared.
The proper way of achieving 1 second interrupts with RTC is to use all alarm mask because this way none of the fields are compared and when the RTC increments the SECOND field an alarm interrupt will be generated.
sAlarm.AlarmMask = RTC_ALARMMASK_ALL;
Also all of this are described by ST in their Using the hardware real-time clock (RTC) in STM32 F0, F2, F3, F4 and L1 series of MCUs application note.
This is a very convenient solution as you do not have to reset the alarm after all interrupts.
As you have set sAlarm.AlarmMask = RTC_ALARMMASK_SECONDS, the RTC will generate an interrupt when the seconds value of the time will match sAlarm.AlarmTime.Seconds which is 0 in your case. So you will have an interrupt every minute here if you leave the code as it is.
If you want an interrupt every second, you will have to set the alarm again with the next second in your interrupt handler. The code in your interrupt handler would look like:
void HAL_RTC_AlarmAEventCallback(RTC_HandleTypeDef *hrtc)
{
RTC_TimeTypeDef sTime;
HAL_RTC_GetTime(&hrtc, &sTime, RTC_FORMAT_BIN);
uint8_t next_second = sTime.Seconds++;
if (next_second > 59) next_second = 0;
RTC_AlarmTypeDef sAlarm;
sAlarm.AlarmTime.Hours = 0;
sAlarm.AlarmTime.Minutes = 0;
sAlarm.AlarmTime.Seconds = RTC_ByteToBcd2(next_second);
sAlarm.AlarmTime.TimeFormat = RTC_HOURFORMAT12_AM;
sAlarm.AlarmTime.DayLightSaving = RTC_DAYLIGHTSAVING_NONE;
sAlarm.AlarmTime.StoreOperation = RTC_STOREOPERATION_RESET;
sAlarm.AlarmMask = RTC_ALARMMASK_SECONDS;
sAlarm.AlarmDateWeekDaySel = RTC_ALARMDATEWEEKDAYSEL_DATE;
sAlarm.AlarmDateWeekDay = 1;
sAlarm.Alarm = RTC_ALARM_A;
HAL_RTC_SetAlarm_IT(&hrtc, &sAlarm, FORMAT_BCD);
}
For this to work, you have to make sure that you have set up properly the RTC clock (internal or external 32K).
Alternatively you could use the wake up function of the RTC, it would be more appropriate I think.
Or in your main loop, you could use the HAL_GetTick to check that 1 second has elapsed since your last processing, like this:
static uint32_t last_second = 0;
void main(void)
{
uint32_t current_second = HAL_GetTick();
if (current_second - last_second > 1000)
{
last_second = current_second;
//1 second has elapsed, do something
}
}
Don't call __HAL_RTC_ALARM_ENABLE_IT() directly. It's called by HAL_RTC_SetAlarm_IT().
Enable Alarm B. Why? Because sometimes, as I've experienced, one alarm won't work. You "sometimes" have to enable both alarms.
For masking, you have to mask all bits:
sAlarm.AlarmMask = RTC_ALARMMASK_DATEWEEKDAY|RTC_ALARMMASK_HOURS|RTC_ALARMMASK_MINUTES|RTC_ALARMMASK_SECONDS;
This way, you ask ST to just use seconds. You can also use RTC_ALARMMASK_ALL.
I have been implementing various forms of simple collision detection with varying results. I have a fairly good working version of collision detection, but there are some odd behaviors that I can't work out.
Just for a reference, i'm making a simple pong game, and trying to refine the collision. The problems I get are when the ball collides with the paddle on either the top or bottom side. In those cases, the ball hovers above (or below) the paddle and does not move. I'm guessing this is because of how i'm checking for collision and how i'm altering the movespeed of the ball.
I would like to implement a way I differentiate between top/bottom and left/right collision but this is the only method that works decently:
static void CheckCollision(PActor object1, PActor object2, PInput pinput)
{
if ( CheckObjectCollision( object1, object2 ) )
{
AdjustMoveSpeed( object1, object2, pinput );
}
}
static bool CheckObjectCollision(PActor object1, PActor object2)
{
int object1LeftBound = object1.position.x;
int object1RightBound = object1.position.x + object1.actorTextureXSize;
int object1TopBound = object1.position.y;
int object1BottomBound = object1.position.y + object1.actorTextureYSize;
int object2LeftBound = object2.position.x;
int object2RightBound = object2.position.x + object1.actorTextureXSize;
int object2TopBound = object2.position.y;
int object2BottomBound = object2.position.y + object2.actorTextureYSize;
if ( object1RightBound < object2LeftBound )
return false;
if ( object1LeftBound > object2RightBound )
return false;
if ( object1BottomBound < object2TopBound )
return false;
if ( object1TopBound > object2BottomBound )
return false;
return true;
}
I am guessing that the root of some of the problems i'm having is the function AdjustMoveSpeed, here it is:
static void AdjustMoveSpeed(PActor object1, PActor object2, PInput pinput)
{
PVector prevMouseLocation = pinput.GetPrevMouseLocation();
PVector currMouseLocation = pinput.GetCurrMouseLocation();
int currentMoveSpeed;
int nextMoveSpeed;
if (typeid(object1) == typeid(PBall))
{
object1.moveSpeed.x *= -1;
if ( typeid(object2) == typeid(PPlayer) )
{
currentMoveSpeed = object1.moveSpeed.y;
nextMoveSpeed = prevMouseLocation.y - currMouseLocation.y;
object1.moveSpeed.y = (prevMouseLocation.y - currMouseLocation.y) * -1;
}
else
{
if (object1.moveSpeed.y > 0)
object1.moveSpeed.y *= -1;
}
}
else if (typeid(object2) == typeid(PBall))
{
object2.moveSpeed.x *= -1;
if ( typeid(object1) == typeid(PPlayer) )
{
currentMoveSpeed = object1.moveSpeed.y;
nextMoveSpeed = prevMouseLocation.y - currMouseLocation.y;
object2.moveSpeed.y = (prevMouseLocation.y - currMouseLocation.y) * -1;
}
else
{
if (object2.moveSpeed.y > 0)
object2.moveSpeed.y *= -1;
}
}
}
What I was attempting to do with AdjustMoveSpeed, is first check to see which object is the ball, after this, multiply the x move speed by -1 to reverse its direction. After this, I check to see if the other object is a player, if so I set the y move speed to the difference between the previous mouse location and current mouse location. This is here to give the player option to change the balls y speed, or add spin.
I've tried checking for intersection between objects so that I can get a specific side, and the result is the ball just flying in the middle of the screen without actually hitting either paddle.
How do I properly check for collision detection on two objects that are squares?
How can I fix AdjustMoveSpeed so that it works properly with collision detection?
Lastly, how do I keep the momentum of the ball of its current speed is greater than the difference of the mouse location before and after the hit?
I've tried taking comparing the absolute value of currentMoveSpeed and nextMoveSpeed but then the ball doesn't change y speed. Something like this:
if ( abs(currentMoveSpeed) < abs(nextMoveSpeed )
object1.moveSpeed.y = (prevMouseLocation.y - currMouseLocation.y) * -1;
else
object1.moveSpeed.y *= -1
Pong is simple enough that, rather than moving the ball each frame and checking for a collision with a paddle, you can actually solve the equation for when the paddle and ball will collide - if that time is less than one frame, there is a collision.
This completely eliminates the issue of the ball moving so fast it moves through the paddle, an issue that plagues many pong-clones that use the naive method of collision-detection.
This solution is called continuous collision detection - see this answer for more information.
If the ball gets stuck on the paddle instead of bouncing it is probably because it keeps changing direction back and forth. The ball should only bounce if it is heading towards the paddle.
if (sgn(object1.moveSpeed.x) == sgn(object1.x - object2.x)) {
// Ball is already moving away from the paddle, don't bounce!
}
else {
// Ok to bounce!
object1.moveSpeed.x *= -1;
}